Dresden 2011 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 89: Methods: other (experimental)

O 89.4: Vortrag

Donnerstag, 17. März 2011, 18:00–18:15, WIL B321

Nanojoule adsorption calorimetry (NAC) and its application to metal/organic interfaces — •Hans-Jörg Drescher, Ole Lytken, Fabian Bebensee, Hans-Peter Steinrück, and J. Michael Gottfried — Universität Erlangen-Nürnberg, Lehrstuhl für Physikalische Chemie II

NAC is a technique for measuring adsorption energies on single-crystals surfaces and other well defined substrates in ultrahigh vacuum. Unlike desorption-based methods such as TPD, it can be used for non-reversible adsorbate systems, in which the adsorbate or substrate decomposes before desorption occurs. Examples include large organic molecules on metal surfaces or metals on organic or polymer surfaces. Similar to previous adsorption calorimeters [1-3], NAC relies on the direct measurement of adsorption-induced temperature changes of thin substrates using pyroelectric detectors. In combination with pulsed molecular beam techniques and highly accurate flux, sticking probability and reflectivity measurements, this ensures outstanding sensitivity in the nanojoule and picomole regimes. This contribution covers design considerations for achieving high accuracies and the challenges arising therefrom. Novel methodical solutions for various classes of interfaces, e.g., metals on semiconducting polymers or π-conjugated organic molecules on metals will be presented. Support by the Alexander von Humboldt Foundation, the DAAD and the Universitätsbund Erlangen-Nürnberg e.V. is gratefully acknowledged. [1] S. Černy, Surf. Sci. Rep. 26 (1996) 1. [2] W. A. Brown et al., Chem. Rev. 98 (1998) 797. [3] O. Lytken et al., Chem. Soc. Rev. 37 (2008) 2172.